Liquid fuel injection pumping apparatus

ABSTRACT

A liquid fuel pumping apparatus for internal combustion engines and which includes a bore which accommodates a reciprocable pumping plunger and which defines a pumping chamber from which extends an outlet. The apparatus also includes a cylinder in which is located a resiliently loaded piston, one end of the cylinder being arranged to be brought into communication with the pumping chamber after the plunger has attained a predetermined position during its injection stroke. In this manner further flow of fuel through the outlet is prevented and relief of the pressure in any apparatus associated with the outlet is obtained.

Unlted States Patent [151 3,663,123 Fenne May 16, 1972 [54] LIQUID FUELINJECTION PUMPING 3,115,838 12/1963 Eoesjter "jig/2g;

3,146,715 9/1964 nu son APPARATUS 3,465,679 9/1969 Adey et a1 ..4l7/284[72] Inventor: Ivor Fenne, Greenford, England Primary Examiner-WilliamL. Freeh [73] Ass1gnee: C. A. V. Llmlted, B1rm1ngham, England A"0meyHolman & Stem 22 Filed: Aug. 11, 1970 [57] ABSTRACT 21 A 1.N 62 972 l 1pp 0 A liquid fuel pumping apparatus for internal combustion engines andwhich includes a bore which accommodates a [30] Foreign ApplicationPriority Data reciprocable pumping plunger and which defines a pumpingchamber from which extends an outlet. The apparatus also in- Aug. 1 1,1969 Great Brltaln ..4Q,010/69 cludes a cylinder in which is located aresi'icmly loaded piston, one end of the cylinder being arranged to bebrought U.S. into communicafion with the chamber after the [51 Int. Cl..F04b 49/00 plunger has attained a predetermined position during itsinjec- [58] Field of Search ..4l7/284, 289, 274, 462, 540, tion stroke.In this manner further flow of fuel through the 417/542 outlet isprevented and relief of the pressure in any apparatus associated withthe outlet is obtained.

6 [5 1 References and 5 Claims, 1 Drawing Figure UNITED STATES PATENTS2,833,218 5/1958 Evans ..4l7/274 LIQUID FUEL INJECTION PUMPING APPARATUSThis invention relates to liquid fuel injection pumping apparatus forinternal combustion engines and of the kind comprising in combination, abore, a reciprocable pumping plunger mounted within said here and anoutlet from the pumping chamber defined by the bore and the plunger,said outlet in use, communicating with an injector mounted on heassociated engine.

The object of the invention is to provide such an apparatus in a simpleand convenient form.

According to the invention an apparatus of the kind specified comprisesa cylinder, a resiliently loaded shuttle mounted in said cylinder, aspill path from said pumping chamber, said spill path communicating withone end of said cylinder, flow of fuel through said spill path occuringduring a pumping stroke of the plunger and being controlled by theplunger, the fuel flowing into said cylinder acting to urge the shuttleagainst the action of its resilient loading and valve means operable toallow the fuel contained in the cylinder to be returned to the pumpingchamber during the next filling stroke of the plunger.

One example of a liquid fuel injection pumping apparatus in accordancewith the invention will now be described with reference to theaccompanying drawing which shows such an apparatus in schematic detailonly.

Referring to the drawing there is provided a body part in which ismounted a rotary cylindrical distributor member 11. The distributormember is arranged to be driven in timed relationship with an engine towhich fuel is supplied by the apparatus and at one end of thedistributor member there is provided a transversely extending bore 12.Mounted within the bore 12 is a pair of pumping plungers 13 and theseare arranged to be moved inwardly as the distributor member rotates, bymeans of a plurality of cam lobes formed in the internal periphery of anannular cam ring 9, which surrounds the distributor member. The pumpingplungers 13 together with the bore 12 define a pumping chamber 14 fromwhich extends a longitudinal passage 15. At its remote end from thepumping chamber the passage 15 communicates with a radially extendingdelivery port which is arranged to register in turn as the distributormember rotates, with a plurality of outlet ports 16 only one of which isshown. The registration of the delivery port with an outlet port 16occurs during the time when the pumping plungers 13 are moved inwardly,and during this time fuel is displaced from the pumping chamber to thedelivery port. The delivery port 16 communicates by way of a pipeline 17with an injection nozzle 18 mounted on the engine in such a manner sothat it directs fuel to a combustion space of the engine.

The passage 15 also communicates with a plurality of inlet ports 19which break out onto the periphery of the distributor member. The inletports register in turn with an inlet passage 20 formed in the body part10 and which communicates with a source of liquid fuel under pressure(not shown). For controlling the flow of fuel through the inlet passage20 there is provided a throttle valve 21 the setting of which can beadjusted by the operator. The arrangement is such that when the deliveryport has moved out of register with an outlet 16, an inlet port 19 movesinto register with the inlet passage 20 and fuel flows to the pumpingchamber 14 to efiect outward movement of the pumping plungers 13.

There is also provided in the body part, a cylinder 22 and mountedwithin the cylinder is a shuttle 23 this being urged towards one end ofthe cylinder by resilient means in the form of a coiled compressionspring 24. The end of the cylinder accommodating the spring 24 is alsoprovided with an adjustable stop 25 and this end of the cylinder is incommunication with a source of fuel at a low pressure. The other end ofthe cylinder communicates with a passage 26 which is arranged toregister with one of the inlet ports 19 at the same time as registrationof one of the other inlet ports with the inlet passage 20 takes place.The same end of the cylinder is also in constant communication with acircumferential groove 27 formed in the periphery of the distributormember and this groove communicates with a pair of spill ports 28 whichopen into the bore 12. The pumping plungers are each provided with apassage 29 whereby at a predetermined position of the pumping plungersduring their inward movement, the pumping chamber will be placed incommunication with the groove 27.

In operation at the start of the inward movement of the pumpingplungers, the passage 26 will be out of register with an inlet port 19and fuel will flow to an outlet 16. At a predetermined position duringthe inward movement of the plungers 13, the passages 29 will be broughtinto register with the ports 28 and when this occurs fuel will flow fromthe pumping chamber by way of the ports 28 and the circumferentialgroove 27 to the cylinder 22. The fuel flow will urge the shuttle 23towards the stop 25. In addition relief of the fuel pressure within theoutlet 16 and pipeline 17 will occur and the shuttle will contact thestop 25. The extent of movement of the shuttle 23 can be controlled bythe stop 25 and this allows adjustment of the maximum quantity of fuelwhich can be supplied at each delivery stroke, to the associated engineby varying the residual pressure in the pipe lines 17.

When the delivery port has moved out of register with an outlet 16 andthe inlet ports 19 move into register with the passages 20 and 26 thefuel previously displaced to the cylinder 22 will be returned to thepumping chamber 14 due to the movement of the shuttle 23 under theaction of the spring 24.

Having thus described my invention whatl claim as new and desire tosecure by Letters Patent is:

l. A liquid fuel injection pumping apparatus and comprising incombination, a bore, a reciprocable pumping plunger mounted within saidbore, said plunger and said bore defining a umping chamber, an outletfrom said pumping chamber, said outlet in use, communicating with aninjector mounted on an associated engine, a cylinder, a resilientlyloaded shuttle mounted in said cylinder, a spill path from said pumpingchamber, said spill path communicating with one end of said cylinder,flow of fuel through said spill path occuring at the end of a pumpingstroke of the plunger and being controlled by the plunger, the fuelflowing into said cylinder acting to urge the shuttle against the actionof its resilient loading and valve means operable to allow the fuelcontained in the cylinder to be returned to the pumping chamber duringthe next filling stroke of the plunger.

2. An apparatus as claimed in claim 1 in which said spill path is inpart defined in said plunger and in part by a port which is formed inthe wall of said bore, said port communicating with said one end of thecylinder.

3. An apparatus as claimed in claim 2 including a rotary distributormember mounted within a body part and arranged to be driven in timedrelationship with the engine with which the apparatus is associated,said cylinder being defined in the body part and the bore being formedin the distributor member, said valve means comprising a second portformed in the body part and in communication with said one end of thecylinder and a third port in the distributor member and whichcommunicates with said pumping chamber.

4. An apparatus as claimed in claim 3 in which a plurality of said thirdports is provided and there is provided in the body part a fourth portwhich is arranged to communicate with a third port when said second portis in communication with a third port, said fourth port communicatingwith a source of a

1. A liquid fuel injection pumping apparatus and comprising incombination, a bore, a reciprocable pumping plunger mounted within saidbore, said plunger and said bore defining a pumping chamber, an outletfrom said pumping chamber, said outlet in use, communicating with aninjector mounted on an associated engine, a cylinder, a resilientlyloaded shuttle mounted in said cylinder, a spill path from said pumpingchamber, said spill path communicating with one end of said cylinder,flow of fuel through said spill path occuring at the end of a pumpingstroke of the plunger and being controlled by the plunger, the fuelflowing into said cylinder acting to urge the shuttle against the actionof its resilient loading and valve means operable to allow the fuelcontained in the cylinder to be returned to the pumping chamber duringthe next filling stroke of the plunger.
 2. An apparatus as claimed inclaim 1 in which said spill path is in part defined in said plunger andin part by a port which is formed in the wall of said bore, said portcommunicating with said one end of the cyliNder.
 3. An apparatus asclaimed in claim 2 including a rotary distributor member mounted withina body part and arranged to be driven in timed relationship with theengine with which the apparatus is associated, said cylinder beingdefined in the body part and the bore being formed in the distributormember, said valve means comprising a second port formed in the bodypart and in communication with said one end of the cylinder and a thirdport in the distributor member and which communicates with said pumpingchamber.
 4. An apparatus as claimed in claim 3 in which a plurality ofsaid third ports is provided and there is provided in the body part afourth port which is arranged to communicate with a third port when saidsecond port is in communication with a third port, said fourth portcommunicating with a source of fuel under pressure to enable the pumpingchamber to be supplied with fuel during the filling strokes of theplunger.
 5. An apparatus as claimed in claim 4 including a stop to limitthe extent of movement of the shuttle against the action of itsresilient loading.